Surfboard rudder-fin combination

ABSTRACT

A surfboard steered by a fin that functions as a rudder in response to force due to gravity of surfer&#39;&#39;s body. A vertical shaft connects the rudder-fin to the surfboard body. Its fixed space relationship in respect to the rudder-fin divides the lateral surface of the rudder-fin into two portions of unequal sizes. The shaft is rotatably mounted in the body of the surfboard. A lever arm adjustable in length is provided between the shaft and body to vary steerability characteristics.

United States Patent Johnson 1 June 24, 1975 SURFBOARD RUDDER-FIN COMBINATION Inventor: Robert F. Johnson, 82 Cambridge Rd. N.W., Calgary, Alberta T2K 1R3, Canada [22] Filed: Feb. 21, 1974 [21] Appl. No.: 444,406

[52] US. Cl. 9/310 B [51] Int. Cl. A63c 15/00 [58] Field of Search 9/310 R, 310 A,31O B, 9/310 E; 114/126 [561' References Cited UNITED STATES PATENTS 3,004510 10/1961 Nawara 114/126 3,579,682 5/1971 Wood 9/310 B Primary Examiner-Duane A. Reger Assistant Examiner-Jesus D. Sotelo Attorney, Agent, or FirmTom Sherrard [5 7] ABSTRACT A surfboard steered by a fin that functions as a rudder in response to force due to gravity of surfers body. A vertical shaft connects the rudder-fin to the surfboard body. Its fixed space relationship in respect to the rudder-fin divides the lateral surface of the rudder-fin into two portions of unequal sizes. The shaft is rotatably mounted in the body of the surfboard. A lever arm adjustable in length is provided between the shaft and body to vary steerability characteristics.

1 Claim, 3 Drawing Figures PMENIEDJUM24 1975 3,890,661

FIG.I

F L9 -8 E l G. 3 ////4 A 1 SURFBOARD RUDDER-FIN COMBINATION BACKGROUND OF THE INVENTION With the rising popularity of surfing the manufacturers of surfboards have provided refined and precision products to accommodate the skills and talents that more and more surfers are developing. Heretofore the fixed fin and lack of moving parts on surfboards has limited opportunities of maneuverability of the board. Some slight directional control of conventional boards is achieved by only the most accomplished surfers but the usual boards cannot be quickly and decisively manipulated for the maximum potential inherent in each wave being ridden to the shore. Ability to steer a board would add new dimensions to surfing in that surfers would then be able to guide the board into, and remain upon, the best part of each wave for optimum surfing. Before my invention there has been no simple, practical means for steering a surfboard.

SUMMARY OF INVENTION In place and instead of the well known fin fixed to a board, l have provided a fin that is slightly rotatable in respect to the body of the board. It is mounted in such a manner that the surfer causes the fin to change alignment with the board merely by changing his position on the board. As a result, he is able to steer the board through the water, on a controlled and desired course, simply by shifting his feet (and thereby body weight) to various places on the board.

BRIEF DESCRIPTION OF DRAWING In the accompanying drawings FIG. I is a perspective sectional view of a portion of my invention showing the connection of the rudder-fin to the surfboard body.

FIG. 2 is a diagram from the end of the board illustrating the resolution of forces which cause my invention to operate.

FIG. 3 is a top plan diagram taken along line 3 of FIG. 1 showing the means for controlling the ease of turning.

DESCRIPTION OF PREFERRED EMBODIMENT In the drawings forming a part hereof wherein like numerals represent like parts throughout, reference numeral l is a body portion of the typical surfboard. My novel components may either be integrated therewith or may be a separate assembly which sets into the body portion in the area where the fin usually attaches. Item 2 is a cap which may be used to retain the described parts. It is essentially a retangular block journalled to retain rotatable shaft 3. The upper portion of shaft 3 may extend into the body as illustrated. It is operatively mounted in the cap and body. An important feature of my invention is the space relationship of the fin and shaft affixed thereto. It is critical that the shaft is not centrally located in the fin. As illustrated in FIG. 1, if the axis of the shaft extended down through the fin it would necessarily divide the fin into two unequal sections 7 and 7'. In this manner, the weight of the surfer, represented by numeral 11, of FIG. 2, on one edge of the board causes, as usual, the edge of surfboard 12 to dip below waterline 13. Resultant natural lateral movement of board in direction of arrow 14 causes resistance of the water, in direction of arrows 15, due to inertia. The total resistance is more on surface section 7 than section 7' because section 7 has greater surface area than section 7'. Since the fin can rotate on shaft 3, section 7 yields to the lateral force of the water and the fin changes its alignment and thereby acts as a rudder. Of course, a shift of the surfers weight to the other side of the board would cause a turning in the opposite direction because of a reversal of all forces. Thus the surfer can steer the board simply by shifting his weight on the board.

Those skilled in the art may devise means to adjust the amount of turn for particular boards and particular surfers without departing from the scope of my invention. For example, I have illustrated one such means. In this assembly retention lever or arm 5 has one end secured to the shaft and it is disposed at right angles thereto. An open space 10 is provided in the body so the arm can freely move when the shaft turns. A retainer 4 has arm 5 projecting through it. The retainer 4 has dual spiral springs 6 and 6 abutting each side of arm 5 to provide desired resistance. To adjust the ease at which the arm, and therefore the fin, may be turned, I have provided dual track 9 with dual securing screws or bolts 8 slideably mounted therein. For great resistance the screws 8 are loosened and slid in track 9 away from the shaft, and then tightened. The resulting long lever arm 5 offers less resistance to turning than if rctainer 4, were placed close to the shaft.

I claim:

1. In combination a. a surfboard body portion,

b. a rudder mounted thereunder,

c. a vertical shaft, one end of which is rotatably mounted in the body portion and the other end of which is integral with the rudder in such space relationship that the two lateral rudder surface portions on each side of the point of integration are unequal in area dimensions,

d. a lever arm secured at right angles to and near the end of the shaft which is rotatably mounted, and

e. resilient means movable in the fore and aft direction relative to the vertical shaft for effectively changing the length of the lever arm to vary the force required for rudder action. 

1. In combination a. a surfboard body portion, b. a rudder mounted thereunder, c. a vertical shaft, one end of which is rotatably mounted in the body portion and the other end of which is integral with the rudder in such space relationship that the two lateral rudder surface portions on each side of the point of integration are unequal in area dimensions, d. a lever arm secured at right angles to and near the end of the shaft which is rotatably mounted, and e. resilient means movable in the fore and aft direction relative to the vertical shaft for effectively changing the length of the lever arm to vary the force required for rudder action. 